JP-A No. 365262/2002 (Patent Document 1) discloses a structure and a method of manufacturing a capillary array which is loaded for use into a multi-capillary electrophoresis apparatus.
The capillary array is provided with a plurality of capillaries and a window unit having an aperture for maintaining alignment of capillaries in the course of the length direction of capillaries to radiate the light to the capillaries and an aperture for detecting information depending on a sample from the capillaries. Moreover, one end of the capillary array is provided with a capillary head for binding and holding the capillaries. A sample injecting end portion of the capillary array is provided with an insulated holder, tubular electrodes fixed to the holder, and a connection plate for connecting the tubular electrodes within the holder. Moreover, there is provided a load header allocated at the upper part of the holder and formed of a cover for insulating contact portions of the connection plate and tubular electrodes from the other portion of the apparatus.
In this load header, tubular electrodes are fixed to a holder consisting of an insulated material and capillaries are inserted to the inside of corresponding tubular electrodes. The tubular electrodes are coupled with each other by the connection plate consisting of an electric conductive material and the connection plate is placed in contact with a high-voltage terminal of the electrophoresis apparatus body to simultaneously load a uniform voltage to a plurality of capillaries.
[Patent Document 1] JP-A No. 36526/2002 (Abstract)
In the load header, the tubular electrodes are fixed to the holder consisting of an insulated resin and the capillaries are inserted into such tubular electrodes. The tubular electrodes are coupled with each other by the connection plate consisting of the electric conductive material to simultaneously apply a voltage to all capillaries.
A conductive portion including the contact portions of the connection plate and tubular electrodes is insulated from the other portion with the cover provided at the upper part of holder to ensure safe operation freed from discharge or electric-shock. In this structure, an air-layer is formed among the connection plate, holder and cover within the load header.
With application of voltage during electrophoresis phenomenon, Joule heat is generated from the capillaries. The Joule heat generated from each capillary is almost equal. However, since the capillaries are arranged like a lattice in the load header and the heat can be easily transferred to the peripheral components in the capillaries located at the external side of load header, temperature of these capillaries is lowered than that of the capillaries located at the internal side (center area) of load header. Meanwhile, in the capillaries located at the internal side, since heat is not easily transferred to the peripheral materials, the heat is not easily radiated, keeping the capillaries under the high temperature condition.
Moreover, since the air-layers are formed between the connection plate and holder and between the cover and tubular electrodes within the load header, the heat insulation effect is generated, further preventing radiation of heat.
Accordingly, temperature gradient is generated depending on the locations of capillaries in the load header, bringing about fluctuation in electrophoresis velocity and resolution among the capillaries.